Generalized program slicing for software maintenance

Program slicing often produces large slices that are still difficult to understand and manipulate, and large program slices usually contain out-of-focus code that distracts the programmer's attention. To overcome these limitations, this paper proposes three ways to extend program slicing: 1) hierarchical slicing, 2) constrained slicing, and 3) recursive slicing. These three extensions facilitate a divide-and-conquer strategy to understand large programs. In addition, this paper also proposes a set of operations for slices, such as union, intersection, and complement of slices, which are useful for a variety of software maintenance activities. We have implemented these extensions in a prototype tool called BRE, which has been demonstrated at several industrial software maintenance sites.